A) Field of the Invention
This invention relates to a blow-off device of a compressor unit, which compressor unit is of the type comprising a compressor to which an outlet conduit is connected with therein a cooler with a moisture separator and a return valve, whereby the blow-off device comprises a blow-off conduit which, on one hand, is connected to the outlet conduit between the cooler and the return valve and, on the other hand, gives out into the atmosphere, and a blow-off valve which is arranged in this blow-off conduit.
B) Related Art
In the known compressor units, an inlet conduit in which a closing valve is provided is connected to the compressor, to which the blow-off valve is coupled in such a manner that, when the closing valve in the inlet conduit is open, respectively closed, the blow-off valve closes, respectively opens, the blow-off conduit.
When this compressor switches from loaded running to unloaded running, the closing valve in the inlet conduit is closed, and consequently the blow-off valve in the blow-off conduit is opened.
The compressed air which is present, among others, in the compressor, in the part of the outlet conduit which is situated between this compressor and the blow-off conduit, and the blow-off conduit itself, suddenly is relieved.
As a result of this sudden and short relief and expansion of the compressed air, the temperature of the compressed air will decrease suddenly and moisture present in the compressed air will condense.
Also, free water from the moisture separator of the cooler will be entrained.
The blown-off compressed air, thus, will comprise moisture particles which are hurled against the housing and other parts of the compressor unit, which causes rust formation and dirt accumulation and is disadvantageous for their service life.
This disadvantage first of all becomes obvious when the compressor is working in humid conditions.